Introduction of a generator using a renewable energy such as photovoltaic power generation (hereinafter, written as “PV”), and wind power generation to a system has been advancing. But, in these power sources, since the output thereof fluctuates depending on the weather, voltage fluctuation resulting from this is generated. Since a voltage exceeds a prescribed value, to cause breakage of an electrical apparatus, it is necessary to suppress voltage fluctuation.
As a method of suppressing voltage fluctuation, there are many methods, such as methods using a power electronics apparatus such as a STATCOM (static synchronous compensator: reactive power compensator) and an SVC (Static Var Compensator: static reactive power compensator), and a method using an apparatus such as an SVR (Step Voltage Regulator: automatic voltage regulator). In the case of using the above-described power electronics apparatus, the voltage fluctuation is suppressed mainly by means of only reactive power. As other methods, a method to use only active power, and a method to use both active power and reactive power can be listed.
However, when an energy storage device represented by a storage battery is used, and voltage fluctuation suppression is performed using active power, since the chargeable amount is determined, when a discharge end state is generated and when a full charge state is generated, the assumed performance might not be obtained.